Digital video compression standards attempt to provide efficient solutions to transfer video. Digital video compression technology reduces the statistical redundancy, perceptual point of view information irrelevancy, and high level features that are redundant across space and time in a source video signal. Compression is represented as compressed frames, where a frame is a snapshot in time. Conventional frames can be of I, P, or B type. I-frames are intra-picture frames compressed using intra-frame coding. P-frames are predicted-picture frames coded using motion-compensated prediction from previously encoded I-frames or P-frames. B-frames are bi-directional predicted picture frames using motion-compensated prediction from previously encoded and/or future encoded I-frames or P-frames. B-frames provide the most compression.
Several successful standards have emerged (e.g., (i) ITU-T H.261: “Video Codec for Audiovisual Services at px64 kbit/s”, Geneve 1990, ITU-T, (ii) H.263: “Video Coding for Low Bitrate Communication”, Geneve 1996, (iii) ISO/IEC MPEG-1 11172-2:1993 Information Technology—Coding of Moving Pictures and Associated Audio for digital storage media at up to 1.5 Mbits/s. Part2, (iv) MPEG-2 ISO/IEC 13818-2:2000 Information Technology—Generic Coding of Moving Pictures and Associated Audio Information. Part2: Video and (v) MPEG-4 ISO/IEC 14496-2:2001 Information Technology—Coding of audio-visual objects. Part 2: Visual), each of which is incorporated by reference in its entirety. These standards address a wide range of applications having different needs in terms of bit rate, picture quality, complexity, error resilience and delay, as well as improved compression ratios.
MPEG-2 encoding has been a key technology used in conventional digital video compression. MPEG-2 does not use B-frames for prediction of other pictures. H.264 encoding provides quality equivalent to MPEG-2, but uses lower bit rates. Alternately, H.264 encoding can provide an improved quality using the same bit rate. However, H.264 encoding is more complex and uses more processing than MPEG-2 encoding. H.264 sometimes uses B-frames for prediction.
The computational needs of conventional digital video encoding compression are extremely high. Compression of digital video without significant quality degradation is usually possible because video sequences contain a high degree of 1) spatial redundancy (due to the correlation between neighboring pixels), 2) spectral redundancy (due to correlation among the color components), 3) temporal redundancy (due to correlation between video frames) and 4) psycho-visual redundancy (due to properties of the human visual system (HVS)).
In conventional video compression standards, since B-frames are not used as reference frames for video compression, the reconstruction process of B-frame encoding may be skipped. Avoiding such reconstruction significantly reduces the computational burden. However, because of various intra-picture prediction modes present in H.264, the reconstruction of B-frames cannot merely be skipped. Therefore, conventional solutions used in MPEG-2 cannot be applied to MPEG-4 Part 10.
It would be desirable to implement a method and/or apparatus to reduce the complexity of video encoding of digital video bitstreams, such as MPEG-4 part 10 compliant bitstreams.